Polishing method using dynamic feedback recipe

ABSTRACT

A polishing method using a dynamic feedback recipe is disclosed. The polishing method includes steps of providing a first recipe, polishing a first wafer according to the first recipe, measuring the first wafer to obtain a first determined data from the first wafer, calculating a second recipe according to a specific equation and the first determined data, and replacing the first recipe with the second recipe and polishing a second wafer according to the second recipe.

FIELD OF THE INVENTION

[0001] The present invention relates to a polishing method using adynamic feedback recipe, and more particularly to a chemical mechanicalpolishing method using a dynamic feedback recipe.

BACKGROUND OF THE INVENTION

[0002]FIG. 1 is a cutaway view illustrating polishing apparatusaccording to the prior art. A wafer 10 is polished by a chemicalmechanical polishing apparatus including a carrier 12 and a carrier film14. Generally, because the polishing rates are different in the centerand the edge of the wafer 10, a back side pressure 11 is applied in thewafer 10 to change the central polishing rate of the wafer 10 forapproaching a consist polishing rate for the whole wafer 10 andachieving a preferred non-uniformity.

[0003] For maintaining the non-uniformity of the wafer 10 in aspecification limit, the methods for using the back side pressure 11 orthe carrier 12 oscillation can reduce the difference between the centraland the edge of the polishing rate. However, along with consuming anddeforming of a polishing pad 13, the central polishing rate of the wafer10 is gradually increased or decreased whereas the edge polishing rateof that is slightly changed. Therefore, the ratio of the central removedamount and the edge removed amount of the wafer is proportional to thenon-uniformity of the wafer.

[0004] Accordingly, the typical polishing method for the wafer includesthe following disadvantages:

[0005] 1. At the beginning of using a new polishing pad, the centralpolishing rate is much faster than the edge polishing rate, whichcausing a poor non-uniformity. Therefore, it is necessary to use a lotof wafers for initially breaking in, a lot of slurry and about 5-10hours to proceed the breaking in. Thus, it really takes time and wastesmaterial.

[0006] 2. At the last phase of the polishing pad, the difference betweenthe central polishing rate and the edge polishing rate is too big andover the specification limit. It is necessary to replace the polishingpad, so the life time of the polishing pad is short.

[0007] 3. The non-uniformity of the wafer is a critical indicator forthe flatness of the wafer. However, the non-uniformity of the waferaccording to the prior art only can be controlled in the specificationlimit, and cannot achieve a preferred condition.

[0008] Therefore, the purpose of the present invention is to develop amethod to deal with the above situations encountered in the prior art.

SUMMARY OF THE INVENTION

[0009] It is therefore an object of the present invention to propose apolishing method using a dynamic feedback recipe for reducing an initialtime of breaking in.

[0010] It is therefore another object of the present invention topropose a polishing method using a dynamic feedback recipe for achievinga preferred non-uniformity of the wafer.

[0011] It is therefore an additional object of the present invention topropose a polishing method using a dynamic feedback recipe forstabilizing a polishing rate of the wafer.

[0012] It is therefore an additional object of the present invention topropose a polishing method using a dynamic feedback recipe forincreasing up time of the production machine, the producing yield, andreducing the cost.

[0013] According to the present invention, there is proposed a polishingmethod using a dynamic feedback recipe. The polishing method includessteps of providing a first recipe, polishing a first wafer according tothe first recipe, measuring the first wafer to obtain a first determineddata from the first wafer, calculating a second recipe according to aspecific equation and the first determined data, and replacing the firstrecipe with the second recipe and polishing a second wafer according tothe second recipe.

[0014] Preferably, each of the first wafer and the second wafercomprises an integrated circuit (IC) thereon.

[0015] Preferably, the first recipe is a predetermined recipe.

[0016] Preferably, the first wafer is driven by a carrier and polishedby a polishing pad via a relative motion. Preferably, the method furtherincludes a carrier film disposed between the carrier and the first waferfor protecting the first wafer. Preferably, the second wafer is drivenby a carrier and polished by a polishing pad via a relative motion.

[0017] Preferably, the polishing method is a chemical mechanicalpolishing method employing a chemical mechanical polishing apparatus.

[0018] Preferably, the specific equation is stored in a dynamic recipecalculating device.

[0019] Certainly, the first recipe and second recipe can be a rotationspeed and a pressure of the carrier, a rotation speed and a pressure ofa turn table in a polishing apparatus, a back side pressure (BSP), aslurry flow rate, a dressing time and a dressing pressure of a padconditioner or a combination thereof.

[0020] Certainly, the first determined data can be obtained by ameasuring apparatus which is disposed in the polishing apparatus or outof the polishing apparatus. Preferably, the first determined data is aratio of a central removed amount and an edge removed amount of thewafer.

[0021] Preferably, the specific equation is y₂=y₁+a (y₀−y₁)+b, and a isthe first determined data, y is a recipe for adjusting, and b is acoefficient.

[0022] Preferably, the polishing method further includes steps ofproviding a plurality of wafers, measuring the second wafer to obtain asecond determined data from the second wafer, calculating a third recipeaccording to the specific equation and the second determined data,replacing the second recipe with the third recipe and polishing a thirdwafer according to the third recipe, and repeating the measuring step,the calculating step, and polishing step to the plural wafers till theplural wafers are polished to obtain a plurality of polished wafers.Preferably, the specific equation is y_(i+2)=y_(i+1)+a(y_(i)−y_(i+1))+b, and a is the first determined data, y is a recipe foradjusting, i is an integer from 0 to n, and b is a coefficient.

[0023] Preferably, the polishing method further includes a testing stepafter polishing for a certain period of time. The testing steppreferably includes providing a test wafer selected from the pluralityof polished wafers, polishing the test wafer according to a testingrecipe, and calculating a removed amount of the test wafer to obtain apolishing rate and an uniformity of the test wafer for determiningwhether to change the polishing pad. Certainly, the test wafer is ablank wafer having a film thereon.

[0024] The present invention may best be understood through thefollowing description with reference to the accompanying drawings, inwhich:

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a cutaway view illustrating polishing apparatusaccording to the prior art;

[0026]FIG. 2 is a flow chart illustrating a polishing method using adynamic feedback recipe according to the present invention; and

[0027] FIGS. 3A-3B are block diagrams illustrating a polishing methodusing a dynamic feedback recipe according to preferred embodiments ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028]FIG. 2 is a flow chart illustrating a polishing method using adynamic feedback recipe according to the present invention. As shown inFIG. 2, after changing a new polishing pad, a blank wafer is providedfor initially breaking in. Sequentially, a first wafer is polished byusing a first recipe. After measuring the first wafer which has beenpolished to obtain a determined data, a second recipe is obtained by aspecific equation. The second recipe is transferred to a chemicalmechanical polishing apparatus for replacing the first recipe and isused for polishing a second wafer. After measuring the second waferwhich has been polished to obtain a second determined data, a thirdrecipe is obtained by the specific equation. The third recipe istransferred to a chemical mechanical polishing apparatus for replacingthe second recipe and is used for polishing a third wafer. Accordingly,a fourth, fifth . . . wafers are polished by the feedback recipes. Thefirst recipe is a predetermined recipe which is tuned by users. Thepredetermined recipe can be changed according to the particularrequirement.

[0029] After a certain period of time or a bath of wafer is polished, atesting step is proceeded to decide whether the polishing pad should bechanged or not. The testing step includes providing a test waferselected from the polished wafers, polishing the test wafer according toa testing recipe, and calculating a removed amount of the test wafer toobtain a polishing rate and an uniformity of the test wafer fordetermining whether to change the polishing pad. The test wafer is ablank wafer with a film thereon. The testing recipe is obtained bytuning. The certain time and the testing recipe can be changed accordingto the particular requirement.

[0030] The chemical mechanical polishing apparatus includes a carrier todrive the wafer for polishing by a polishing pad via a relative motion.The carrier has a carrier film between the carrier and the wafer forprotecting the wafer. Each wafer has an integrated circuit thereon.

[0031] The above recipes includes a carrier rotation speed, a carrierpressure, a rotation speed and a pressure of a turn table in thepolishing apparatus, a back side pressure (BSP), a slurry flow rate, adressing time and a dressing pressure of a pad conditioner or acombination thereof.

[0032] The specific equation stored in a dynamic recipe calculatingdevice is y_(i+2)=y_(i+1)+a (y_(i)−y_(i+1))+b, wherein a is the firstdetermined data, y is a recipe for adjusting, i=0˜n and b is acoefficient. The first determined data is a ratio of a central removedamount and an edge removed amount of the wafer.

[0033] As shown in FIGS. 3A and 3B, the predetermined preset recipe,e.g. the first recipe is inputted into a central information manager(CIM) computer 32, and transferred from the central information managercomputer 32 to a dynamic recipe calculating device 31. A compensatedrecipe, e.g. the second recipe is calculated and obtained by the dynamicrecipe calculating device 31 according to the specific equation and thefirst determined data, and transferred back to the central informationmanager computer 32. Finally, the compensated recipe is transferred to achemical mechanical polishing apparatus 30 for polishing the wafer.

[0034] In addition, a measuring apparatus 33 is disposed in the chemicalmechanical polishing apparatus 30 as shown in FIG. 3B whereas ameasuring apparatus (not shown) is disposed out of the chemicalmechanical polishing apparatus 30 as shown in FIG. 3A. Thus, thedetermined data is automatically obtained by the measuring apparatus 33and is feedback to the dynamic recipe calculating device 31 as shown inFIG. 3B. However, when the measuring apparatus is out of the chemicalmechanical polishing apparatus 30, the polished wafer is taken to themeasuring apparatus by operators to measure the determined data, and thedetermined data is inputted to the central information manager computer32 by operators. The measuring apparatus is in situ.

[0035] In sum, the polishing method using the dynamic feedback recipeaccording to the present invention can efficiently solve the problems ofthe long initial time for breaking in and the short life time of thepolishing pad. In addition, the polishing method can achieve thepreferred non-uniformity of the wafer, stabilize the polishing rate,increase the producing yield, and reduce the slurry consumption.

[0036] While the invention has been described in terms of what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention need not to be limited to thedisclosed embodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

What is claimed is:
 1. A polishing method using a dynamic feedbackrecipe, comprising steps of: providing a first recipe; polishing a firstwafer according to said first recipe; measuring said first wafer toobtain a first determined data from said first wafer; calculating asecond recipe according to a specific equation and said first determineddata; and replacing said first recipe with said second recipe andpolishing a second wafer according to said second recipe.
 2. The methodaccording to claim 1, wherein each of said first wafer and said secondwafer comprises an integrated circuit (IC) thereon.
 3. The methodaccording to claim 1, wherein said first recipe is a predeterminedrecipe.
 4. The method according to claim 1, wherein said first wafer isdriven by a carrier and polished by a polishing pad via a relativemotion.
 5. The method according to claim 4, further comprising a carrierfilm disposed between said carrier and said first wafer for protectingsaid first wafer.
 6. The method according to claim 1, wherein saidsecond wafer is driven by a carrier and polished by a polishing pad viaa relative motion.
 7. The method according to claim 1, wherein saidpolishing method is a chemical mechanical polishing method employing achemical mechanical polishing apparatus.
 8. The method according toclaim 1, wherein said specific equation is stored in a dynamic recipecalculating device.
 9. The method according to claim 1, wherein saidfirst recipe and second recipe are selected from one group consisting ofa rotation speed and a pressure of said carrier, a rotation speed and apressure of a turn table in a polishing apparatus, a back side pressure(BSP), a slurry flow rate, a dressing time and a dressing pressure of apad conditioner and a combination thereof.
 10. The method according toclaim 9, wherein said first determined data is obtained by a measuringapparatus which is disposed in said polishing apparatus.
 11. The methodaccording to claim 9, wherein said first determined data is obtained bya measuring apparatus which is disposed out of said polishing apparatus.12. The method according to claim 1, wherein said first determined datais a ratio of a central removed amount and an edge removed amount ofsaid wafer.
 13. The method according to claim 1, wherein said specificequation is y₂=y₁+a (y₀−y₁)+b, and a is said first determined data, y isa recipe for adjusting, and b is a coefficient.
 14. The method accordingto claim 1, further comprising steps of: providing a plurality ofwafers; measuring said second wafer to obtain a second determined datafrom said second wafer; calculating a third recipe according to saidspecific equation and said second determined data; replacing said secondrecipe with said third recipe and polishing a third wafer according tosaid third recipe; and repeating said measuring step, said calculatingstep, and polishing step to said plural wafers till said plural wafersare polished to obtain a plurality of polished wafers.
 15. The methodaccording to claim 14, wherein said specific equation isy_(i+2)=y_(i+1)+a (y_(i)−y_(i−1))+b, and a is said first determineddata, y is a recipe for adjusting, i=0˜n and b is a coefficient.
 16. Themethod according to claim 14, further comprising a testing step afterpolishing for a certain period of time.
 17. The method according toclaim 16, wherein said testing step comprises: providing a test waferselected from said plurality of polished wafers; polishing said testwafer according to a testing recipe; and calculating a removed amount ofsaid test wafer to obtain a polishing rate and an uniformity of saidtest wafer for determining whether to change said polishing pad.
 18. Themethod according to claim 17, wherein said test wafer is a blank waferhaving a film thereon.